I dont really think it's smart of people to be throwing 'my old friend' around all of the time but I also feel that in alot of cases people CHOOSE to be offended, there are alot of things people say that I disagree with or find stupid, but I am not offended by it, it takes alot for someone to offend me just by saying something, it would have to be a really direct and personal thing to offend me outright.
If someone is offended by someone typing "my old friend" then I'd say they should probably learn to brush it off because this is the internet and you'll have plenty of people call you a "my old friend" over the time you spend on it and in most cases feeling 'offended' and running to mother isn't going to have the person punished. At the same time I wouldn't agree with someone harassing another person over it, there's a difference though. If I kill someone and they say "my old friend", I laugh to myself, but if someone keeps pursuing it and keeps throwing random insults at me simply because I killed them, whatever the words they use, then yes I believe they should be punished, because that's just bad conduct and very childish.
You my old friends.